Cannabidiol as a treatment for epilepsy

Journal of Neurology

“Despite an increasing number of anti-epileptic drugs (AEDs), the proportion of drug-resistant cases of epilepsy has remained fairly static at around 30% and the search for new and improved AEDs continues.

Cannabis has been used as a medical treatment for epilepsy for thousands of years; it contains many active compounds, the most important being tetrahydrocannabinol, which has psychoactive properties, and cannabidiol, which does not.

Animal models and clinical data to date have suggested that cannabidiol is more useful in treating epilepsy; there is limited evidence that tetrahydrocannabinol has some pro-convulsant effects in animal models. The mechanism by which cannabidiol exerts its anti-convulsant properties is currently unclear.

Conclusion. The evidence is increasing that cannabidiol is an effective treatment option for childhood onset severe treatment-resistant epilepsies with a tolerable side effect and safety profile. Further evidence is needed before cannabidiol can be considered in more common or adult onset epilepsies. Longer-term safety data for cannabidiol, particularly considering its effects on the developing brain, are also required.”

https://link.springer.com/article/10.1007%2Fs00415-017-8663-0

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Efficacy and safety of cannabis for treating children with refractory epilepsy.

Nursing Children and Young People

“The aim of this literature review was to examine the evidence base for the safety and efficacy of cannabis in treating children with refractory epilepsy. Clinical and medical databases were searched and four articles were included in the final analysis, which included retrospective reviews and open-label trials with a total sample size of 424. One clinical trial included administration of cannabidiol, the non-psychoactive compound of cannabis, while the other three articles stated that the compound administered to participants contained tetrahydrocannabidiol, the psychoactive constituent of cannabis.

Cannabis may reduce seizures in some children and young people with refractory epilepsy, however, its success may be affected by aetiology of the epilepsy or concomitant anti-epileptic drug use, and a therapeutic dose has not been found. Positive side effects were also found including improved sleep, alertness and mood. More research is needed on this subject, including randomised controlled trials. Nurses who are aware of patients and families wishing to trial cannabis for refractory epilepsy should have full and frank discussions.”

https://www.ncbi.nlm.nih.gov/pubmed/29115760

https://journals.rcni.com/nursing-children-and-young-people/efficacy-and-safety-of-cannabis-for-treating-children-with-refractory-epilepsy-ncyp.2017.e907

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Trial of Cannabidiol for Drug-Resistant Seizures in the Dravet Syndrome

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“BACKGROUND

The Dravet syndrome is a complex childhood epilepsy disorder that is associated with drug-resistant seizures and a high mortality rate. We studied cannabidiol for the treatment of drug-resistant seizures in the Dravet syndrome.

METHODS

In this double-blind, placebo-controlled trial, we randomly assigned 120 children and young adults with the Dravet syndrome and drug-resistant seizures to receive either cannabidiol oral solution at a dose of 20 mg per kilogram of body weight per day or placebo, in addition to standard antiepileptic treatment. The primary end point was the change in convulsive-seizure frequency over a 14-week treatment period, as compared with a 4-week baseline period.

RESULTS

The median frequency of convulsive seizures per month decreased from 12.4 to 5.9 with cannabidiol, as compared with a decrease from 14.9 to 14.1 with placebo (adjusted median difference between the cannabidiol group and the placebo group in change in seizure frequency, −22.8 percentage points; 95% confidence interval [CI], −41.1 to −5.4; P=0.01). The percentage of patients who had at least a 50% reduction in convulsive-seizure frequency was 43% with cannabidiol and 27% with placebo (odds ratio, 2.00; 95% CI, 0.93 to 4.30; P=0.08). The patient’s overall condition improved by at least one category on the seven-category Caregiver Global Impression of Change scale in 62% of the cannabidiol group as compared with 34% of the placebo group (P=0.02). The frequency of total seizures of all types was significantly reduced with cannabidiol (P=0.03), but there was no significant reduction in nonconvulsive seizures. The percentage of patients who became seizure-free was 5% with cannabidiol and 0% with placebo (P=0.08). Adverse events that occurred more frequently in the cannabidiol group than in the placebo group included diarrhea, vomiting, fatigue, pyrexia, somnolence, and abnormal results on liver-function tests. There were more withdrawals from the trial in the cannabidiol group.

CONCLUSIONS

Among patients with the Dravet syndrome, cannabidiol resulted in a greater reduction in convulsive-seizure frequency than placebo and was associated with higher rates of adverse events. (Funded by GW Pharmaceuticals; ClinicalTrials.gov number, NCT02091375.)”

http://www.nejm.org/doi/10.1056/NEJMoa1611618

“Cannabinoids for Epilepsy — Real Data, at Last”  http://www.nejm.org/doi/full/10.1056/NEJMe1702205

“Cannabidiol (CBD) Significantly Reduces Convulsive Seizure Frequency in Dravet Syndrome (DS): Results of a Multi-center, Randomized, Double-blind, Placebo-controlled Trial (GWPCARE1)” http://files.shareholder.com/downloads/AMDA-1TW341/201889199x0x919787/73B57FA6-CD45-4ABB-8C89-87EFEA36B4ED/1332B_AES_Poster_Dravet_Part_B_.pdf

“EPILEPSY AND MARIJUANA: CANNABIS DRUG REDUCES DRAVET SYNDROME SEIZURES IN LARGE-SCALE CLINICAL TRIAL” http://www.newsweek.com/cannabis-marijuana-dravet-syndrome-epilepsy-clinical-trial-614982

“Study proves medicinal cannabis can help children with severe epilepsy, researchers say” http://www.abc.net.au/news/2017-05-25/scientific-study-medicinal-cannabis-helps-children-with-epilepsy/8556180
 
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The Direct Actions of Cannabidiol and 2-Arachidonoyl Glycerol at GABAA Receptors.

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“Cannabidiol (CBD) is a major non-intoxicating component of cannabis and possesses anti-epileptic, anxiolytic and anti-hyperalgesic properties.

Despite evidence that some endogenous and synthetic cannabinoids interact with GABAA receptors, no-one has yet investigated the effects of CBD.

Here we used two-electrode voltage clamp electrophysiology to compare the actions of CBD with those of the major central endocannabinoid, 2-arachidonoyl glycerol (2-AG) on human recombinant GABAA receptors (synaptic α1-6βg2 and extrasynaptic α4β2δ) expressed on Xenopus oocytes.

Taken together these results reveal a mode of action of CBD on specifically configured GABAA receptors that may be relevant to the anticonvulsant and anxiolytic effects of the compound.”

https://www.ncbi.nlm.nih.gov/pubmed/28249817

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Cannabinoids and epilepsy — Introduction.

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“Over the past five years, the lay press and families of children with catastrophic epilepsies popularized the use of cannabis and cannabinoids to treat seizures. Many state legislatures have responded to the pressure from lay groups and have legalized medical cannabis, which is now available to a majority of people in the United States. Patients throughout the world are also obtaining and using cannabinoids to treat their epilepsy. There is an enormous dissociation between the widespread use of cannabis-based therapies to treat diverse epilepsies and our understanding about the efficacy and safety of different cannabinoids in treating different epilepsy syndromes.”  http://www.epilepsybehavior.com/article/S1525-5050(17)30042-2/abstract

http://www.thctotalhealthcare.com/category/epilepsy-2/

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Therapeutic effects of cannabinoids in animal models of seizures, epilepsy, epileptogenesis, and epilepsy-related neuroprotection.

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“The isolation and identification of the discrete plant cannabinoids in marijuana revived interest in analyzing historical therapeutic claims made for cannabis in clinical case studies and anecdotes. In particular, sources as old as the 11th and 15th centuries claimed efficacy for crude marijuana extracts in the treatment of convulsive disorders, prompting a particularly active area of preclinical research into the therapeutic potential of plant cannabinoids in epilepsy.

Since that time, a large body of literature has accumulated describing the effects of several of the >100 individual plant cannabinoids in preclinical models of seizures, epilepsy, epileptogenesis, and epilepsy-related neuroprotection. We surveyed the literature for relevant reports of such plant cannabinoid effects and critically reviewed their findings.

We found that acute CB1R agonism in simple models of acute seizures in rodents typically produces anti-convulsant effects whereas CB1R antagonists exert converse effects in the same models. However, when the effects of such ligands are examined in more complex models of epilepsy, epileptogenesis and neuroprotection, a less simplistic narrative emerges.

Here, the complex interactions between (i) brain regions involved in a given model, (ii) relative contributions of endocannabinoid signaling to modulation of synaptic transmission in such areas, (iii) multi-target effects, (iv) cannabinoid type 1 and type 2 receptor signaling interactions and, (v) timing, (vi) duration and (vii) localization of ligand administration suggest that there is both anti-epileptic therapeutic potential and a pro-epileptic risk in up- and down-regulation of endocannabinoid signaling in the central nervous system.

Factors such receptor desensitization and specific pharmacology of ligands used (e.g. full vs partial agonists and neutral antagonists vs inverse agonists) also appear to play an important role in the effects reported.

Furthermore, the effects of several plant cannabinoids, most notably cannabidiol (CBD) and cannabidavarin (CBDV), in models of seizures, epilepsy, epileptogenesis, and neuroprotection are less ambiguous, and consistent with reports of therapeutically beneficial effects of these compounds in clinical studies.

However, continued paucity of firm information regarding the therapeutic molecular mechanism of CBD/CBDV highlights the continued need for research in this area in order to identify as yet under-exploited targets for drug development and raise our understanding of treatment-resistant epilepsies.

The recent reporting of positive results for cannabidiol treatment in two Phase III clinical trials in treatment-resistant epilepsies provides pivotal evidence of clinical efficacy for one plant cannabinoid in epilepsy.

Moreover, risks and/or benefits associated with the use of unlicensed Δ9-THC containing marijuana extracts in pediatric epilepsies remain poorly understood.

Therefore, in light of these paradigm-changing clinical events, the present review’s findings aim to drive future drug development for newly-identified targets and indications, identify important limitations of animal models in the investigation of plant cannabinoid effects in the epilepsies, and focuses future research in this area on specific, unanswered questions regarding the complexities of endocannabinoid signaling in epilepsy.”

https://www.ncbi.nlm.nih.gov/pubmed/28190698

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Cannabinoids in treatment-resistant epilepsy: A review.

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“Treatment-resistant epilepsy (TRE) affects 30% of epilepsy patients and is associated with severe morbidity and increased mortality.

Cannabis-based therapies have been used to treat epilepsy for millennia, but only in the last few years have we begun to collect data from adequately powered placebo-controlled, randomized trials (RCTs) with cannabidiol (CBD), a cannabis derivative.

Previously, information was limited to case reports, small series, and surveys reporting on the use of CBD and diverse medical marijuana (MMJ) preparations containing: tetrahydrocannabinol (THC), CBD, and many other cannabinoids in differing combinations.

These RCTs have studied the safety and explored the potential efficacy of CBD use in children with Dravet Syndrome (DS) and Lennox-Gastaut Syndrome (LGS).

The role of the placebo response is of paramount importance in studying medical cannabis products given the intense social and traditional media attention, as well as the strong beliefs held by many parents and patients that a natural product is safer and more effective than FDA-approved pharmaceutical agents.

We lack valid data on the safety, efficacy, and dosing of artisanal preparations available from dispensaries in the 25 states and District of Columbia with MMJ programs and online sources of CBD and other cannabinoids. On the other hand, open-label studies with 100mg/ml CBD (Epidiolex®, GW Pharmaceuticals) have provided additional evidence of its efficacy along with an adequate safety profile (including certain drug interactions) in children and young adults with a spectrum of TREs.

Further, Phase 3 RCTs with Epidiolex support efficacy and adequate safety profiles for children with DS and LGS at doses of 10- and 20-mg/kg/day. This article is part of a Special Issue titled “Cannabinoids and Epilepsy”.”

https://www.ncbi.nlm.nih.gov/pubmed/28188044

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A case for cannabidiol in Wolf-Hirschhorn syndrome seizure management.

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“Complex, and sometimes intractable, seizures affect the quality of life and cognitive development of over 90% of individuals with Wolf-Hirschhorn syndrome (WHS). Fine resolution genotype-phenotype mapping of the WHS locus recently identified a candidate gene whose probable function has led to insights into a mechanism connecting WHS seizures with those of Dravet syndrome, a distinct condition caused by mutations in SCN1A and SCN1B. In addition to this possible molecular mechanistic connection, these disorders’ seizures share a strikingly similar constellation of features, including clinical presentation, seizure types, early age of onset, EEG pattern, and responses to specific anti-epileptic drugs. Based in part on these similarities, we suggest that a highly successful Phase III clinical trial of a formulation of cannabidiol for Dravet syndrome seizures may be directly translatable into possible benefits for WHS individuals with challenging seizure patterns.”

https://www.ncbi.nlm.nih.gov/pubmed/28102593

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Endogenous cannabinoid system alterations and their role in epileptogenesis after brain injury in rat.

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“Post-traumatic epilepsy (PTE) is one of the most common complications resulting from brain injury, however, antiepileptic drugs usually fail to prevent it.

Several lines of evidence have demonstrated that the endogenous cannabinoid system (ECS) plays a pivotal role during epileptogenesis in several animal models.

A recent study has shown that a cannabinoid type 1 (CB1) receptor antagonist could suppress long-term neuron hyperexcitability after brain injury, but the underlying mechanisms remain largely unknown.

In this study, we first analyzed the dynamic expression of different components of the ECS at various time points after brain injury in rats. Then, we conducted a 12-month-long session of behavioral monitoring after the brain injury, and based on the results, the rats were divided into a PTE group and a non-PTE group. Finally, the changes in the ECS between the two groups were compared.

We found that the ECS exhibited a biphasic alteration after brain injury; the expression of the CB1 receptor and 2-arachidonoylglycerol (2-AG) in the PTE group was significantly higher than that of the non-PTE group 12 months after traumatic brain injury.

Our preliminary results indicated that the ECS might be involved in post-traumatic epileptogenesis.”

https://www.ncbi.nlm.nih.gov/pubmed/27810514

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Crucial Roles of the Endocannabinoid 2-Arachidonoylglycerol in the Suppression of Epileptic Seizures.

“Endocannabinoid signaling is considered to suppress excessive excitability of neural circuits and to protect the brain from seizures. However, the precise mechanisms of this effect are poorly understood.

Here, we report that 2-arachidonoylglycerol (2-AG), one of the two major endocannabinoids, is crucial for suppressing seizures.

We found that kainate-induced seizures in mice lacking the 2-AG synthesizing enzyme, diacylglycerol lipase α, were much more severe compared with those in cannabinoid CB1 receptor knockout mice and were comparable to those in mice lacking both CB1– and CB2-receptor-mediated signaling.

In the dentate gyrus, 2-AG suppressed excitatory input around the inner and middle molecular layers through CB1 and presumably CB2 receptors, respectively.

This 2-AG-mediated suppression contributed to decreased granule cell excitability and the dampening of seizures. Furthermore, lack of 2-AG signaling enhanced kindling epileptogenesis and spontaneous seizures after kainate-induced status epilepticus.

These results highlight critical roles of 2-AG signaling in the suppression of epileptic seizures.”

http://www.ncbi.nlm.nih.gov/pubmed/27452464

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